Add support for server interceptor filtering

This commit adds support for filtering the server-side global interceptors.

The server factory is now passed down through the service discoverer and
configurer to allow the filter to take into account the server factory in
use.

The service discoverer contract has also been minimized to remove the
unused `findService(String)` method.

Resolves #208

Signed-off-by: Chris Bono <chris.bono@gmail.com>

Author: onobc

spring-grpc-core/src/main/java/org/springframework/grpc/server/ServerInterceptorFilter.java

@@ -0,0 +1,42 @@
+/*
+ * Copyright 2023-2025 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.grpc.server;
+
+import io.grpc.BindableService;
+import io.grpc.ServerInterceptor;
+
+/**
+ * Strategy to determine whether a global {@link ServerInterceptor} should be included for
+ * a given {@link BindableService service} and {@link GrpcServerFactory server factory}.
+ *
+ * @author Chris Bono
+ */
+@FunctionalInterface
+public interface ServerInterceptorFilter {
+
+	/**
+	 * Determine whether the given {@link ServerInterceptor} should be included for the
+	 * provided {@link BindableService service} and {@link GrpcServerFactory server
+	 * factory}.
+	 * @param interceptor the server interceptor under consideration.
+	 * @param serverFactory the server factory in use.
+	 * @param service the service being added.
+	 * @return {@code true} if the interceptor should be included; {@code false}
+	 * otherwise.
+	 */
+	boolean filter(ServerInterceptor interceptor, GrpcServerFactory serverFactory, BindableService service);
+
+}

spring-grpc-core/src/main/java/org/springframework/grpc/server/ServletGrpcServerFactory.java

@@ -0,0 +1,45 @@
+/*
+ * Copyright 2024-2025 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.grpc.server;
+
+import io.grpc.Server;
+import io.grpc.ServerServiceDefinition;
+
+/**
+ * Marker interface for {@link GrpcServerFactory} that is to be handled by the servlet
+ * container.
+ *
+ * @author Chris Bono
+ */
+public class ServletGrpcServerFactory implements GrpcServerFactory {
+
+	/**
+	 * Default instance of marker interface.
+	 */
+	public static ServletGrpcServerFactory INSTANCE = new ServletGrpcServerFactory();
+
+	@Override
+	public Server createServer() {
+		throw new UnsupportedOperationException("Marker interface only");
+	}
+
+	@Override
+	public void addService(ServerServiceDefinition service) {
+		throw new UnsupportedOperationException("Marker interface only");
+	}
+
+}

spring-grpc-core/src/main/java/org/springframework/grpc/server/service/DefaultGrpcServiceConfigurer.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2023-2024 the original author or authors.
+ * Copyright 2023-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -20,10 +20,16 @@
 import java.util.List;
 
 import org.springframework.beans.factory.InitializingBean;
+import org.springframework.beans.factory.NoSuchBeanDefinitionException;
+import org.springframework.beans.factory.NoUniqueBeanDefinitionException;
 import org.springframework.context.ApplicationContext;
+import org.springframework.core.log.LogAccessor;
 import org.springframework.grpc.internal.ApplicationContextBeanLookupUtils;
 import org.springframework.grpc.server.GlobalServerInterceptor;
+import org.springframework.grpc.server.GrpcServerFactory;
+import org.springframework.grpc.server.ServerInterceptorFilter;
 import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
 
 import io.grpc.BindableService;
 import io.grpc.ServerInterceptor;
@@ -38,37 +44,49 @@
  */
 public class DefaultGrpcServiceConfigurer implements GrpcServiceConfigurer, InitializingBean {
 
+	private final LogAccessor log = new LogAccessor(getClass());
+
 	private final ApplicationContext applicationContext;
 
 	private List<ServerInterceptor> globalInterceptors;
 
+	private ServerInterceptorFilter interceptorFilter;
+
 	public DefaultGrpcServiceConfigurer(ApplicationContext applicationContext) {
 		this.applicationContext = applicationContext;
 	}
 
 	@Override
 	public void afterPropertiesSet() {
 		this.globalInterceptors = findGlobalInterceptors();
+		this.interceptorFilter = findInterceptorFilter();
 	}
 
 	@Override
-	public ServerServiceDefinition configure(BindableService bindableService, @Nullable GrpcServiceInfo serviceInfo) {
-		return bindInterceptors(bindableService, serviceInfo);
+	public ServerServiceDefinition configure(GrpcServerFactory serverFactory, BindableService bindableService,
+			@Nullable GrpcServiceInfo serviceInfo) {
+		Assert.notNull(serverFactory, () -> "serverFactory must not be null");
+		Assert.notNull(bindableService, () -> "bindableService must not be null");
+		return bindInterceptors(serverFactory, bindableService, serviceInfo);
 	}
 
 	private List<ServerInterceptor> findGlobalInterceptors() {
 		return ApplicationContextBeanLookupUtils.getBeansWithAnnotation(this.applicationContext,
 				ServerInterceptor.class, GlobalServerInterceptor.class);
 	}
 
-	private ServerServiceDefinition bindInterceptors(BindableService bindableService,
+	private ServerServiceDefinition bindInterceptors(GrpcServerFactory serverFactory, BindableService bindableService,
 			@Nullable GrpcServiceInfo serviceInfo) {
 		var serviceDef = bindableService.bindService();
 		if (serviceInfo == null) {
 			return ServerInterceptors.interceptForward(serviceDef, this.globalInterceptors);
 		}
-		// Add global interceptors first
+		// Add and filter global interceptors first
 		List<ServerInterceptor> allInterceptors = new ArrayList<>(this.globalInterceptors);
+		if (this.interceptorFilter != null) {
+			allInterceptors
+				.removeIf(interceptor -> !this.interceptorFilter.filter(interceptor, serverFactory, bindableService));
+		}
 		// Add interceptors by type
 		Arrays.stream(serviceInfo.interceptors())
 			.forEachOrdered(
@@ -84,4 +102,20 @@ private ServerServiceDefinition bindInterceptors(BindableService bindableService
 		return ServerInterceptors.interceptForward(serviceDef, allInterceptors);
 	}
 
+	private ServerInterceptorFilter findInterceptorFilter() {
+		try {
+			return this.applicationContext.getBean(ServerInterceptorFilter.class);
+		}
+		catch (NoUniqueBeanDefinitionException noUniqueBeanEx) {
+			this.log.warn(noUniqueBeanEx,
+					() -> "No unique ServerInterceptorFilter bean found. Consider defining a single bean or marking one as @Primary");
+			return null;
+		}
+		catch (NoSuchBeanDefinitionException ignored) {
+			this.log.debug(
+					() -> "No ServerInterceptorFilter bean found - filtering will not be applied to server interceptors.");
+			return null;
+		}
+	}
+
 }

spring-grpc-core/src/main/java/org/springframework/grpc/server/service/DefaultGrpcServiceDiscoverer.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2023-2024 the original author or authors.
+ * Copyright 2023-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -20,10 +20,13 @@
 
 import org.springframework.context.ApplicationContext;
 import org.springframework.grpc.internal.ApplicationContextBeanLookupUtils;
+import org.springframework.grpc.server.GrpcServerFactory;
 import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
 
 import io.grpc.BindableService;
 import io.grpc.ServerServiceDefinition;
+import io.grpc.ServiceDescriptor;
 
 /**
  * The default {@link GrpcServiceDiscoverer} that finds all {@link BindableService} beans
@@ -44,12 +47,25 @@ public DefaultGrpcServiceDiscoverer(GrpcServiceConfigurer serviceConfigurer,
 	}
 
 	@Override
-	public List<ServerServiceDefinition> findServices() {
+	public List<ServerServiceDefinition> findServices(GrpcServerFactory serverFactory) {
+		Assert.notNull(serverFactory, () -> "serverFactory must not be null");
 		return ApplicationContextBeanLookupUtils
 			.getOrderedBeansWithAnnotation(this.applicationContext, BindableService.class, GrpcService.class)
 			.entrySet()
 			.stream()
-			.map((e) -> this.serviceConfigurer.configure(e.getKey(), this.serviceInfo(e.getValue())))
+			.map((e) -> this.serviceConfigurer.configure(serverFactory, e.getKey(), this.serviceInfo(e.getValue())))
+			.toList();
+	}
+
+	@Override
+	public List<String> listServiceNames() {
+		return ApplicationContextBeanLookupUtils
+			.getOrderedBeansWithAnnotation(this.applicationContext, BindableService.class, GrpcService.class)
+			.keySet()
+			.stream()
+			.map(BindableService::bindService)
+			.map(ServerServiceDefinition::getServiceDescriptor)
+			.map(ServiceDescriptor::getName)
 			.toList();
 	}
 

spring-grpc-core/src/main/java/org/springframework/grpc/server/service/GrpcServiceConfigurer.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2023-2024 the original author or authors.
+ * Copyright 2023-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,6 +16,7 @@
 
 package org.springframework.grpc.server.service;
 
+import org.springframework.grpc.server.GrpcServerFactory;
 import org.springframework.lang.Nullable;
 
 import io.grpc.BindableService;
@@ -31,10 +32,13 @@ public interface GrpcServiceConfigurer {
 
 	/**
 	 * Configure and bind a gRPC service.
+	 * @param serverFactory the factory that provides the server the service will be added
+	 * to
 	 * @param bindableService service to bind and configure
 	 * @param serviceInfo optional additional service information
 	 * @return configured service definition
 	 */
-	ServerServiceDefinition configure(BindableService bindableService, @Nullable GrpcServiceInfo serviceInfo);
+	ServerServiceDefinition configure(GrpcServerFactory serverFactory, BindableService bindableService,
+			@Nullable GrpcServiceInfo serviceInfo);
 
 }

spring-grpc-core/src/main/java/org/springframework/grpc/server/service/GrpcServiceDiscoverer.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2023-2024 the original author or authors.
+ * Copyright 2023-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -18,6 +18,8 @@
 
 import java.util.List;
 
+import org.springframework.grpc.server.GrpcServerFactory;
+
 import io.grpc.ServerServiceDefinition;
 
 /**
@@ -26,36 +28,20 @@
  * @author Michael (yidongnan@gmail.com)
  * @author Chris Bono
  */
-@FunctionalInterface
 public interface GrpcServiceDiscoverer {
 
 	/**
-	 * Find gRPC services for the server to provide.
+	 * Find all gRPC services.
+	 * @param serverFactory the factory that provides the server that the services are to
+	 * be added to
 	 * @return list of services to add to the server - empty when no services available
 	 */
-	List<ServerServiceDefinition> findServices();
+	List<ServerServiceDefinition> findServices(GrpcServerFactory serverFactory);
 
 	/**
-	 * Find gRPC service names.
+	 * Find names of all gRPC services.
 	 * @return list of service names - empty when no services available
 	 */
-	default List<String> listServiceNames() {
-		return findServices().stream()
-			.map(ServerServiceDefinition::getServiceDescriptor)
-			.map(descriptor -> descriptor.getName())
-			.toList();
-	}
-
-	/**
-	 * Find gRPC service.
-	 * @param name the service name
-	 * @return a service - null if no service has this name
-	 */
-	default ServerServiceDefinition findService(String name) {
-		return findServices().stream()
-			.filter(service -> service.getServiceDescriptor().getName().equals(name))
-			.findFirst()
-			.orElse(null);
-	}
+	List<String> listServiceNames();
 
 }